Note that you are using My.Computer.FileSystem.FileExists(sFilepath & "\" & sFileName) instead of your trimmed string.

Update: Maybe your path contains invalid characters. You could use a method to remove them:

ReadOnly InvalidPathChars As String = New String(Path.GetInvalidPathChars())
Public Function RemoveInvalidPathChars(dirOrFileName As String) As String
dirOrFileName = dirOrFileName.Trim()
For Each c As Char In InvalidPathChars
dirOrFileName = dirOrFileName.Replace(c, "")
Next
Return dirOrFileName
End Function